President Obama has restated his call for high earners in ______ United States to pay more in____ taxes , in his first news conference since winning re-election.

A．the; /

B．/;/

C．/;the

D．a; the

跳伞运动员在“中华第一高楼”--上海金茂大厦进行跳伞．运动员从345m的高度跳下，下落过程中运动员的重力势能______（选填“增大”“不变”或“减小”）；若下落时间为30s，则全程的平均速度为______m/s，若以______为参照物，运动员是静止的．